May 1997 arXiv papers — page 14

Ya-Sha Yi, Tie-Zheng Qian, Zhao-Bin Su

We consider the motion of electrons through a mesoscopic ring in the presence of spin-orbit interaction, Zeeman coupling, and magnetic flux. The coupling between the spin and the orbital degrees of freedom results in the geometric and the dynamical phases associated with a cyclic evolution of spin state. Using a non-adiabatic Aharonov-Anandan phase approach,

Manny Rayner, David Carter, Ivan Bretan, Robert Eklund

We describe two methods relevant to multi-lingual machine translation systems, which can be used to port linguistic data (grammars, lexicons and transfer rules) between systems used for processing related languages. The methods are fully implemented within the Spoken Language Translator system, and were used to create versions of the system for two new langu

E. E. Fenimore, M. C. Sumner

In many models of Gamma-Ray Bursts (GRBs) relativistic shells are responsible for the overall envelope of emission. We use kinematics and symmetry to calculate the time history and spectral evolution expected from a relativistic shell including effects from intrinsic variations in the shell's intensity and spectra. We find that the decay phase of an enve

Pablo Dmitruk, Daniel O. Gomez

We perform direct numerical simulations of an externally driven two-dimensional magnetohydrodynamic system over extended periods of time to simulate the dynamics of a transverse section of a solar coronal loop. A stationary and large-scale magnetic forcing was imposed, to model the photospheric motions at the magnetic loop footpoints. A turbulent stationary

F. H. Briggs

The Fisher-Tully `10 Mpc Catalog of Late-Type Galaxies&#39; (FT, 1981) is remarkably complete. Despite the considerable effort that has been spent searching for and cataloging low surface brightness (LSB) galaxies, almost no new HI-rich galaxies have been added to the volume to which the FT observations were both sensitive (d < 10 (M_{HI}/10^{8.2} Msolar)^{5

Thomas A. Barlow, F. Hamann, W. L. W. Sargent

It is possible to distinguish ``intrinsic&#39;&#39; absorption systems (gas clouds within the quasar environment) from ``intervening&#39;&#39; systems (gas clouds unrelated to the quasar phenomenon) by considering certain observational properties. We find that the most direct determinations of the intrinsic nature of a system are time variability and partial

J. C. Vega, E. M. Corsini, A. Pizzella, F. Bertola

We measured the velocity curve and the velocity dispersion profile of the ionized gas along the major axis of the edge-on galaxy UGC~10205. The observed kinematics extends up to about 40 arcsec from the nucleus. In the inner 13 arcsec of this early-type spiral three kinematically distinct gaseous components are present. We disentangle a fast-rotating and a s

HongSheng Zhao

Non-uniqueness of deprojecting the integrated light distribution of a nearby or faraway triaxial body is reviewed in the context of deriving the volume density of the Galactic bar from the COBE/DIRBE maps of the Galactic plane. The exact origin of this non-uniqueness is studied. One can write down a sequence of triaxial bar models which appear identical in i

Alvaro De Rujula

An elegantly symmetric Universe, consisting of large islands of matter and antimatter, is by no means obviously out of the question. I review the observations that lead to the usual prejudice that the Universe contains only matter. I discuss recent work inferring that this prejudice can be converted into an inescapable conclusion. I argue that our theoretica

M. Jaroszynski, A. Kurpiewski

We investigate advection dominated, transsonic accretion flows in the vicinity of a Kerr black hole. We take into account all relativistic effects in the dynamics of the flow and in the propagation of light. We assume the matter to be weakly magnetized and cool via the thermal synchrotron and Bremsstrahlung radiation. We include also the effects of Comptoniz

K. D. Gordon, D. Calzetti, A. N. Witt

To investigate the nature of starbursts&#39; dust, we constructed a model of the stars and dust in starburst galaxies and applied it to 30 observed starburst spectral energy distributions (SEDs). The starburst model was constructed by combining two stellar evolutionary synthesis models with a model describing the radiative transfer of stellar photons through

Ron Y. Donagi

This is a survey of the work of Seiberg and Witten on 4-dimensional N=2 supersymmetric Yang-Mills theory and of some of its recent extensions, written for mathematicians. The point of view is that of algebraic geometry and integrable systems. An introductory chapter tries to describe some of the relevant physics for a reader with no physics background. This

David C. Butler

Let $C$ be a smooth projective irreducible curve of genus $g$. And let $G_α(n,d,l)$ be the moduli space of $α$ stable pairs of a vector bundle of $\rank n, °d$ and a subspace of $H^0(C,E)$ of $\dim = l $. We find an explicit birational map from $G_α (n, d, n+1)$ to $G_α (1, d, n+1)$ for $C$ general, $1/α\gg 0$ and $g \ge n^2-1$. Because of this and other exa

Xiangdong Shi

When Cold Dark Matter (CDM) power spectrum normalized by COBE results, its amplitude at smaller scales can be parametrized by $Γ\simΩ_0h$. The expected variations of Hubble flows in two samples, the sample of 36 clusters in the Mark III catalogue, and the sample of 20 Type Ia supernovae (SNe), are calculated for the power spectrum in critical-density CDM mod

Sanghyeon Chang, Claudio Coriano, R. D. Field, L. E. Gordon

We present the complete $O(α_s^2)$ radiative corrections to the (non singlet) polarized Drell Yan cross section for the production of a lepton pair with a nonzero $q_T$. The helicity of the incoming states is arbitrary. In the case of double photon, results for the longitudinal asymmetries and on the $p_T$ behavior of the cross section are also given (to $O(

Sanghyeon Chang, Claudio Coriano, R. D. Field, L. E. Gordon

A study of the order $α_s^2$ corrections to the Drell Yan (non-singlet) cross section for incoming states of arbitrary longitudinal helicities is presented. The study is performed in the case of the transverse momentum distributions, $(q_T)$, of the lepton pair and extends the calculation of Ellis Martinelli and Petronzio (EMP) to the polarized case. We use

Richard D. Saam

A theoretical framework supported by literature reported experimental evidence (Homes, Harshman along with Voyager, Hubble and EGRET space platforms and others) is presented which indicates that superconductivity is a self energy phenomenon and congruent with the concept of the Charge Conjugation, Parity Change and Time Reversal (CPT) theorem. A resonant sym

Guy D. Moore

We measure the diffusion constant for Chern-Simons number for classical, lattice SU(3) Yang-Mills theory, using a generalization of the topological definition of Chern-Simons number developed recently by Moore and Turok. The diffusion constant is much larger than that for SU(2), even before the ratio of coupling constants has been accounted for, which implie

Mark Mineev-Weinstein

Using our exact time-depending solutions, we solve the Saffman-Taylor finger selection problem in the absence of surface tension by showing that an arbitrary interface in a Hele-Shaw cell evolves to a single uniformly advancing finger occupying one half of the channel width. This result contradicts the generally accepted belief that surface tension is indisp

J. J. Halliwell

We use the decoherent histories approach to quantum theory to derive the form of an effective theory describing the coupling of classical and quantum variables. The derivation is carried out for a system consisting of a large particle coupled to a small particle with the important additional feature that the large particle is also coupled to a thermal enviro

A. A. Zvyagin, H. Johannesson, M. Granath

We present the exact Bethe Ansatz solution of a multichannel model of one- dimensional correlated electrons coupled antiferromagnetically to a magnetic impurity of arbitrary spin S. The solution reveals that interactions in the bulk make the magnetic impurity drive both spin and charge fluctuations, producing a mixed valence at the impurity site, with an ass

V. D. Ivashchuk, V. N. Melnikov

A multidimensional gravitational model containing several dilatonic scalar fields and antisymmetric forms is considered. The manifold is chosen in the form M = M_0 x M_1 x ... x M_n, where M_i are Einstein spaces (i > 0). The block-diagonal metric is chosen and all fields and scale factors of the metric are functions on M_0. For the forms composite (electro-

U. Lisenfeld, A. Ferrara

We have compared the metallicity (represented by oxygen abundance), and the dust-to-gas ratio, in a sample of dwarf galaxies. For dwarf irregulars (dIrrs) we find a good correlation between the two quantities, with a power-law index ${0.54\pm 0.2}$. Blue Compact Dwarf (BCD) galaxies do not show such a good correlation; in addition both the dust-to-gas ratio

Pierre Sikivie

It is shown that the infall of collisionless dark matter onto isolated galaxies produces a series of caustic rings in the halo dark matter distribution. The properties of these caustics are investigated. The density profile of the caustic is derived for a specific case. Bumps in the rotation curve of NGC 3198 are interpreted as due to caustic rings of dark m

A. Bartl, E. Christova, T. Gajdosik, W. Majerotto

The CP violating electric and weak dipole moment form factors of the top quark appear in the process $e^{+}e^{-} --> t\bar{t}$. We present a complete analysis of these dipole moment form factors within the Minimal Supersymmetric Standard Model with complex parameters. We include gluino, chargino, and neutralino exchange in the loop of the $\gamma t\bar{t}$ a

Mark Bowick, Emmanuel Guitter

We study the tubular phase of self-avoiding anisotropic membranes. We discuss the renormalizability of the model Hamiltonian describing this phase and derive from a renormalization group equation some general scaling relations for the exponents of the model. We show how particular choices of renormalization factors reproduce the Gaussian result, the Flory th

S. Bertolini, J. O. Eeg, M. Fabbrichesi, E. I. Lashin

We calculate the hadronic matrix elements to $O(p^4)$ in the chiral expansion for the ($ΔS =1$) $K^0 \to 2 π$ decays and the ($ΔS=2$) $\bar K^0$-$K^0$ oscillation. This is done within the framework of the chiral quark model. The chiral coefficients thus determined depend on the values of the quark and gluon condensates and the constituent quark mass. We show

G. karra, R. J. Rivers

We calculate the initial density of relativistic global vortices (strings) produced at a quench and contrast it with the predictions of Kibble and Zurek.

M. J. E. Richardson

The reaction process $A+B->C$ is modelled for ballistic reactants on an infinite line with particle velocities $v_A=c$ and $v_B=-c$ and initially segregated conditions, i.e. all A particles to the left and all B particles to the right of the origin. Previous, models of ballistic annihilation have particles that always react on contact, i.e. pair-reaction pro

Lorenz von Smekal, Andreas Hauck, Reinhard Alkofer

A solvable systematic truncation scheme for the Dyson-Schwinger equations of Euclidean QCD in Landau gauge is presented. It implements the Slavnov-Taylor identities for the three-gluon and ghost-gluon vertices, whereas irreducible four-gluon couplings as well as the gluon-ghost and ghost-ghost scattering kernels are neglected. The infrared behavior of gluon

Mikhail Plyushchay

A universal minimal spinor set of linear differential equations describing anyons and ordinary integer and half-integer spin fields is constructed with the help of deformed Heisenberg algebra with reflection. The construction is generalized to some d=2+1 supersymmetric field systems. Quadratic and linear forms of action functionals are found for the universa

K. Frieler, K. -H. Rehren

Kadanoff&#39;s &#34;correlations along a line&#34; in the critical two-dimensional Ising model (1969) are reconsidered. They are the analytical aspect of a representation of abelian chiral vertex operators as quadratic polynomials, in the sense of operator valued distributions, in non-abelian exchange fields. This basic result has interesting applications to

Anatol N. Kirillov

We study some quadratic algebras which are appeared in the low-dimensional topology and Schubert calculus. We introduce the Jucys-Murphy elements in the braid algebra and in the pure braid group, as well as the Dunkl elements in the extended affine braid group. Relationships between the Dunkl elements, Dunkl operators and Jucys-Murphy elements are described.

Michal Horodecki, Ryszard Horodecki

We prove within the standard quantum formalism without reduction postulate that the no-cloning theorem and the principle of no-increasing of entanglement under local actions and one-way classical communication are equivalent. We argue that the result is a manifestation of more general principles governing quantum information processing analogous to the therm

J. R. Walsh, G. Dudziak, D. Minniti, A. A. Zijlstra

Spectrophotometry and imaging of the two planetary nebulae He2-436 and Wray16-423, recently discovered to be in the Sagittarius dwarf elliptical galaxy, are presented. Wray16-423 is a high excitation planetary nebula (PN) with a hot central star. In contrast He2-436 is a high density PN with a cooler central star and evidence of local dust, the extinction ex

Yoshiyuki Y. Yamaguchi

A new universality of Lyapunov spectra {λ_i} is shown for Hamiltonian systems. The universality appears in middle energy regime and is different from another universality which can be reproduced by random matrices in the following two points. One is that the new universality appears in a limited range of large i/N rather than the whole range, where N is degr

I. G. Korepanov

In paper IV (solv-int/9704013) we have considered a string living in the infinite lattice that was, in a sense, generated by a &#34;particle&#34;. Here we show how to construct multi-string eigenstates generated by several particles. It turns out that, at least in some cases, this allows us to bypass the difficulties of constructing multi-particle states. We

A. V. Tsiganov

In this work we consider superintegrable systems in the classical $r$-matrix method. By using other authomorphisms of the loop algebras we construct new superintegrable systems with rational potentials from geodesic motion on $R^{2n}$.

O. V. Man&#39;ko, N. V. Tcherniega

New time-dependent integrals of motion are found for stimulated Raman scattering. Explicit formula for the photon-number probability distribution as a function of the laser-field intensity and the medium parameters is obtained in terms of Hermite polynomials of two variables.

P. Ohberg, E. L. Surkov, I. Tittonen, S. Stenholm

Bogolyubov-De Gennes equations for the excitations of a Bose condensate in the Thomas-Fermi regime in harmonic traps of any asymmetry and introduce a classification of eigenstates. In the case of cylindrical symmetry we emphasize the presence of an accidental degeneracy in the excitation spectrum at certain values of the projection of orbital angular momentu

U. Kagan, E. L. Surkov, G. V. Shlyapnikov

We develop the idea of selectively manipulating the condensate in a trapped Bose-condensed gas, without perturbing the thermal cloud. The idea is based on the possibility to modify the mean field interaction between atoms (scattering length) by nearly resonant incident light or by spatially uniform change of the trapping magnetic field. For the gas in the Th

K. J. Eskola, K. Kajantie, P. V. Ruuskanen

We compute the longitudinal hydrodynamic flow in ultrarelativistic heavy ion collisions at $\sqrt{s}$ = 5500 GeV by using boost non-invariant initial conditions following from perturbative QCD. The transfer of entropy and energy from the central region to larger rapidities caused by boost non-invariance is determined and the associated decrease in the lifeti

J. Cleymans, M. Marais, E. Suhonen

Relativistic heavy ion collisions are studied assuming that particles can be described by a hadron gas in thermal and chemical equilibrium. The exact conservation of baryon number, strangeness and charge are explicitly taken into account. For heavy ions the effect arising from the neutron surplus becomes important and leads to a substantial increase in e.g.

Matthias R. Gaberdiel, Barton Zwiebach

The possible tensor constructions of open string theories are analyzed from first principles. To this end the algebraic framework of open string field theory is clarified, including the role of the homotopy associative A_\infty algebra, the odd symplectic structure, cyclicity, star conjugation, and twist. It is also shown that two string theories are off-she

Michael S. Turner, Erick J. Weinberg

The pre-big-bang cosmology inspired by superstring theories has been suggested as an alternative to slow-roll inflation. We analyze, in both the Jordan and Einstein frames, the effect of spatial curvature on this scenario and show that too much curvature --- of either sign --- reduces the duration of the inflationary era to such an extent that the flatness a

Zheng Huang, Hung Jung Lu, Ina Sarcevic

We investigate the nuclear shadowing mechanism in the context of perturbative QCD and the Glauber multiple scattering model. Using recent HERA data on nucleon structure function at small $x$, we put stringent constrains on the nucleon gluon density in the double-logarithm approximation. We suggest that the scaling violation of the nucleon structure function

Sanatan Digal, Supratim Sengupta, Ajit M. Srivastava

We carry out numerical simulation of a first order phase transition in 2+1 dimensions by randomly nucleating bubbles, and study the formation of global U(1) vortices. Bubbles grow and coalesce and vortices are formed at junctions of bubbles via standard Kibble mechanism as well as due to a new mechanism, recently proposed by us, where defect-antidefect pairs

J. C. Montero, A. A. Natale, P. S. Rodrigues da Silva

Nonperturbative infrared finite solutions for the gluon polarization tensor have been found, and the possibility that gluons may have a dynamically generated mass is supported by recent Monte Carlo simulation on the lattice. These solutions differ among themselves, due to different approximations performed when solving the Schwinger-Dyson equations for the g

K. G. Chetyrkin, B. A. Kniehl, M. Steinhauser

We present in analytic form the three-loop O(α_s^2) correction to the H -> gg partial width of the standard-model Higgs boson with intermediate mass M_H << 2 M_t. Its knowledge is required because the O(α_s) correction is so sizeable that the theoretical prediction to this order is unlikely to be reliable. For M_H=100 GeV, the resulting QCD correction factor

Yoshio Koide

A seesaw mass matrix model is reviewed as a unification model of quark and lepton mass matrices. The model can understand why top-quark mass m_t is so singularly enhanced compared with other quark masses, especially, why m_t >> m_b in contrast to m_u = O(m_d), and why only top-quark mass is of the order of the electroweak scale Lambda_W, i.e., m_t = O(Lambda

K. Kimura, K. Tesima

The collimation $C$ of a hadronic event in the e^+e^- annihilation is defined as the average of $\cosθ$, $C=<\cosθ>$, where $θ$ is the angle of each hadron measured from the thrust axis, and the average is over all the hadrons produced in an event. It is an infrared-stable event-shape parameter. $1-\bar C$, the difference between the unity and the average co

Masako Bando

We propose that the difference of dynamical gauge bosons in asymptotically non-free (ANF) gauge thoeries from elementary ones is the existence of the compositeness condition at some scale $Lambda$. This shall be explained by using non-linear Grassmannian like model where dynamical gauge bosons are generated associated with the hidden local symmetry. Then we

D. Korotkin, H. Samtleben

The canonical quantization of the essentially nonlinear midisuperspace model describing cylindrically symmetric gravitational waves with two polarizations is presented. A Fock space type representation is constructed. It is based on a complete set of quantum observables. Physical expectation values may be calculated in arbitrary excitations of the vacuum. Ou

Vladimir D. Ivashchuk

The Wick rotation in quantum field theory is considered in terms of analytical continuation in the signature matrix parameter w = eta_00. Regularization of propagators by a complex metric parameter in most cases preserves (i) the convergence of Feynmann integrals (understood as Lebesgue integrals) if the corresponding integrals of Euclidean theory are conver

R. B. Mann

I demonstrate that, under certain circumstances, regions of negative energy density can undergo gravitational collapse into a black hole. The resultant exterior black hole spacetimes necessarily have negative mass and non-trivial topology. A full theory of quantum gravity, in which topology-changing processes take place, could give rise to such spacetimes.

M. Letz, K. Ziegler

A two dimensional model for quantum percolation with variable tunneling range is studied. For this purpose the Lifshitz model is considered where the disorder enters the Hamiltonian via the nondiagonal elements. We employ a numerical method to analyze the level statistics of this model. It turns out that the level repulsion is strongest around the percolatio

Gene F. Mazenko

The vortex velocity probability distribution for two distinct vortices is determined for the case of phase-ordering kinetics in systems with point defects. The n-vector model driven by time-dependent Ginzburg-Landau dynamics for a nonconserved order parameter is considered. The description includes the effects of other vortices and order parameter fluctuatio

Dirk K. Morr, Andrey V. Chubukov

Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-$T_c$ materials. Recent experiments have shown a strong dependence of the Raman signal in $B_{1g}$ geometry on the frequency of the incoming photon. We present an analytical and numerical study of the Raman intensity in the reso

N K Wilkin, J M F Gunn, R A Smith

Motivated by experiments on bose atoms in traps which have attractive interactions (e.g. ^7Li), we consider two models which may be solved exactly. We construct the ground states subject to the constraint that the system is rotating with angular momentum proportional to the number of atoms. In a conventional system this would lead to quantised vortices; here

Martin Greiter

It is argued that there is no low-energy resonance associated with the pi-operators introduced by Demler and Zhang. This implies that the Hubbard model does not possess an approximate SO(5) symmetry generated by these operators. Recent finite-size studies are re-interpreted accordingly.

Kedar Damle, Satya N. Majumdar, Subir Sachdev

We study the approach to equilibrium of a Bose gas to a superfluid state. We point out that dynamic scaling, characteristic of far from equilibrium phase-ordering systems, should hold. We stress the importance of a non-dissipative Josephson precession term in driving the system to a new universality class. A model of coarsening in d=2, involving a quench bet

D. Sornette, L. Knopoff

We show analytically that the answer to the question, &#34;The longer it has been since the last earthquake, the longer the expected time till the next ?&#34; depends crucially on the statistics of the fluctuations in the interval times between earthquakes. The periodic, uniform, semigaussian, Rayleigh and truncated statistical distributions of interval time

P. Zinn-Justin

The behavior of correlation functions is studied in a class of matrix models characterized by a measure $\exp(-S)$ containing a potential term and an external source term: $S=N\tr(V(M)-MA)$. In the large $N$ limit, the short-distance behavior is found to be identical to the one obtained in previously studied matrix models, thus extending the universality of

V. Yu. Irkhin

A derivation of the t-J model of a highly-correlated solid is given starting from the general many-electron Hamiltonian with account of the non-orthogonality of atomic wave functions. Asymmetry of the Hubbard subbands (i.e. of ``electron&#39;&#39; and ``hole&#39;&#39;cases) for a nearly half-filled bare band is demonstrated. The non-orthogonality corrections

P. Bantay, G. Zala

The consequences of replica-symmetry breaking on the structure of ultrametric matrices appearing in the theory of disordered systems is investigated with the help of representation theory, and the results are compared with those obtained by Temesvari, De Dominicis and Kondor.

Gerhard Fasol, Katharina Runge

A selective electrodeposition method for the fabrication of extremely thin and long metallic and magnetic wires and other nanostructures is introduced. Growth is done on the cleaved edge of a semiconductor multilayer structure incorporating a 4 nm wide modulation doped quantum well. This conducting quantum well is connected to the negative current contact du

Steven H. Simon, Patrick A. Lee

Volovik and Kopnin make two seperate points regarding our recent paper (S. H. Simon and P. A. Lee, PRL 78, 1548 (1997); cond-mat/9611133). First they note that the scaling regime we address in our paper is limited by the curvature of the Fermi surface, and secondly they note that the crossover scale derived in our paper is incorrect. These points are valid a

Stefan Riezler

Constraint logic grammars provide a powerful formalism for expressing complex logical descriptions of natural language phenomena in exact terms. Describing some of these phenomena may, however, require some form of graded distinctions which are not provided by such grammars. Recent approaches to weighted constraint logic grammars attempt to address this issu

Hang Li, Kenji Yamanishi

We propose a new method of classifying documents into categories. The simple method of conducting hypothesis testing over word-based distributions in categories suffers from the data sparseness problem. In order to address this difficulty, Guthrie et.al. have developed a method using distributions based on hard clustering of words, i.e., in which a word is a

P. Seba, F. Haake, M. Kus, M. Barth

We demonstrate both theoretically and experimentally that the distribution of the wavefunction inside a partially open chaotic timereversal symmetric system displays significant deviations from the Porter Thomas distribution. We give arguments which show that this distribution resembles the distribution which is expected to be found in closed chaotic systems

R. Michael Rich, Craig Sosin, S. George Djorgovski, Giampaolo Piotto

We have used WFPC2 to construct B, V color-magnitude diagrams of four metal-rich globular clusters, NGC 104 (47 Tuc), NGC 5927, NGC 6388, and NGC 6441. All four clusters have well populated red horizontal branches (RHB), as expected for their metallicity. However, NGC 6388 and 6441 also exhibit a prominent blue HB (BHB) extension, including stars reaching as

Andrew King, Ulrich Kolb, Ewa Szuszkiewicz

We consider transient behavior in low-mass X-ray binaries. In short-period neutron-star systems (orbital period less than ~ 1d) irradiation of the accretion disk by the central source suppresses this except at very low mass transfer rates. Formation constraints however imply that a significant fraction of these neutron star systems have nuclear-evolved main-

V. Castellani, F. Ciacio, S. Degl&#39;Innocenti, G. Fiorentini

This paper discusses low mass, metal poor stars, presenting new evolutionary computations which take into account the inward diffusion of both He and heavy elements during the H burning phase. The investigation has been extended to He burning models, discussing the luminosity of the Zero Age Horizontal Branch (ZAHB) models originated from progenitors with ef

A. C. Goncalves, P. Veron, M. -P. Veron-Cetty

We observed 37 AGN candidates and classified them on the basis of their spectroscopic properties; three are confirmed QSOs, one is a BL Lac object, nine are Seyfert 1 galaxies, four Seyfert 2s, while twenty are HII regions.

Avishai Dekel

Cosmological implications of the observed large-scale peculiar velocities are reviewed, alone or combined with redshift surveys and CMB data. The latest version of the POTENT method for reconstructing the underlying three-dimensional velocity and mass-density fields is described. The initial fluctuations and the nature of the dark matter are addressed via st

J. -R. Roy, J. R. Walsh

Emission-line optical spectrophotometry for 55 H II regions in the prominent southern barred spiral galaxy NGC 1365 is presented. Nebular diagnostic diagrams such as [N II]/[O II] and [S II]/[O II] versus [O II]/{O III] show that the H II regions of the barred galaxy have the same range of physical conditions as found in non-barred late-type galaxies. Extinc

J. R. Walsh, J. -R. Roy

Multi-fibre emission-line spectrophotometry of 33 H II regions and 3 diffuse interstellar medium positions are presented for the barred Magellanic galaxy NGC 1313. The H II regions show a fairly narrow range of thermal conditions characteristic of high excitation nebular gas. Electron temperature was directly determined in four of the H II regions. The globa

E. E. Fenimore

We calculate the expected envelope of emission for relativistic shells under the assumption of local spherical symmetry. Gamma-Ray Burst envelopes rarely conform to the expected shape, which is similar to a FRED; a fast rise and exponential decay. The fast rise is determined by the time that the relativistic shell prodcues gamma rays. The decay has the form

Kota Yoshioka

Under some assumptions, we compute the Picard group of moduli of stable sheaves on Abelian surfaces. Considering relative moduli spaces, it is sufficient to consider the moduli of stable sheaves on the product of elliptic curves. By using elementary transformatios (which was used by Friedman to treat rank 2 moduli spaces on elliptic surfaces), we treat this

Barak Kol

5-brane configurations describing 5d field theories are promoted to an M theory description a la Witten in terms of polynomials in two complex variables. The coefficients of the polynomials are the Coulomb branch. This picture resolves apparent singularities at vertices and reveals exponentially small corrections. These corrections ask to be compared to worl

John Cardy, Jesper Lykke Jacobsen

The effect of quenched impurities on systems which undergo first-order phase transitions is studied within the framework of the q-state Potts model. For large q a mapping to the random field Ising model is introduced which provides a simple physical explanation of the absence of any latent heat in 2D, and suggests that in higher dimensions such systems shoul

Julie D. Blum, Kenneth Intriligator

We discuss consistency conditions for branes at orbifold singularities. The conditions have a world-sheet interpretation in terms of tadpole cancellation and a space-time interpretation in terms of anomalies. As examples, we consider type II and type I branes on $C^2/Z_M$ orbifolds. We give orientifold constructions of phases of type I or heterotic string th

H. Verlinde

The existence two S-dual descriptions of (N,1) string bound states suggests that the strong coupling behaviour of electric flux lines in large N 2D SYM theory has a dual description in terms of weakly coupled IIB string theory. In support of this identification, we propose a dual interpretation of the SYM loop equation as a perturbative string Ward identity,

N. G. Deshpande, B. Dutta, Xiao-Gang He

We reexamine the contact interaction hypothesis for excess high-$Q^2$ events seen at HERA in $e^+ p \to e^+ X$ scattering. We consider the most general structure of contact interactions insisting on $SU(3)_C\times SU(2)_L \times U(1)_Y$ invariance. Apart from constraints for $e^+ e^- \to q\bar q$ , Drell-Yan and atomic parity violation experiments, we find s

Ted Jacobson

Decay of a near-extremal black hole down to the extremal state is studied in the background field approximation to determine the fate of injected matter and Hawking pairs. By examining the behavior of light rays and solutions to the wave equation it is concluded that the singularity at the origin is irrelevant. Furthermore, there is most likely an instabilit

Stavros Garoufalidis, Hiroaki Nakamura

We consider several algebras that arise in the study of the mapping class group (by means of topology and Hodge theory) and describe their symplectic-invariant parts in terms of algebras on trivalent graphs.

V. D. Ivashchuk, V. N. Melnikov, M. Rainer

We consider a gravitational model on a manifold M = M_0 x M_1 x...x M_n with oriented connected Einstein internal spaces M_1,...,M_n. The matter part of the action contains several scalar fields and antisymmetric forms. With Ricci-flat internal spaces, the model has a midisuperspace representation in form of a sigma-model on M_0. The latter can be used to de

Arya Akmal, Vijay R. Pandharipande

We report variational calculations of symmetric nuclear matter and pure neutron matter, using the new Argonne v18 two-nucleon and Urbana IX three-nucleon interactions. At the equilibrium density of 0.16 fm^-3 the two-nucleon densities in symmetric nuclear matter are found to exhibit a short-range spin-isospin structure similar to that found in light nuclei.

Norbert Dragon, Sergei Kuzenko

We describe the Higgs mechanism for general N=2 super Yang-Mills theories in a manifestly supersymmetric form based on the harmonic superspace.

Uwe Trittmann, Hans-Christian Pauli

Quantum field theories in front-form dynamics are not manifestly rotationally invariant. We study a model bound-state equation in 3+1 dimensional front-form dynamics, which was shown earlier to reproduce the Bohr and hyperfine structure of positronium. We test this model with regard to its rotational symmetry and find that rotational invariance is preserved

I. Antoniadis, M. Quiros

We argue that supersymmetry breaking by gaugino condensation in the strongly coupled heterotic string can be described by an analogue of Scherk-Schwarz compactification on the eleventh dimension in M-theory. The M-theory scale is identified with the gauge coupling unification mass, whereas the radius of the eleventh dimension $ρ$ is at an intermediate scale

Jerome P. Gauntlett

Exact duality in supersymmetric gauge theories leads to highly non-trivial predictions about the moduli spaces of BPS monopole solutions. These notes attempt to be a pedagogical review of the current status of these investigations and are based on lectures given at the 33rd Karpacz Winter School: Duality - Strings and Fields, February 1997.

Ilka Brunner, Andreas Karch

We analyze brane configurations corresponding to non-trivial six dimensional fixed points. Several results previously obtained from a pure field theoretical analysis are rederived in the brane language.

Rafael D. Sorkin

Although we have convincing evidence that a black hole bears an entropy proportional to its surface (horizon) area, the ``statistical mechanical&#39;&#39; explanation of this entropy remains unknown. Two basic questions in this connection are: what is the microscopic origin of the entropy, and why does the law of entropy increase continue to hold when the ho

B. Holdom

We discuss how CP violation originating in the right-handed neutrino sector can feed into the quark sector, in an otherwise CP invariant theory. The dominant effects are superweak, and we suggest that this may yield a natural resolution of the strong CP problem. This work builds on and extends a previously proposed model of quark and lepton masses, based on

M. P. Locher, V. E. Markushin, H. Q. Zheng

A coupled channel model is used to study the nature of the f0(980) resonance. It is shown that the existence of two poles close to KKbar threshold, as found in many data fits and confirmed here, can be reconciled with the KKbar molecular origin of the f0(980). Due to a strong coupling between channels the number of the S-matrix poles close to the physical re

The Baikal Collaboration

We review the present status of the Baikal Neutrino Project. The construction and performance of the large deep underwater Cherenkov detector for muons and neutrinos, NT-200, which is currently under construction in Lake Baikal are described. Some results obtained with the first stages of NT-200 - NT-36 (1993-95), NT-72 (1995-96) and NT-96 (1996-97) - are pr

L. Vanzo

The Einstein&#39;s equations with a negative cosmological constant admit solutions which are asymptotically anti-de Sitter space. Matter fields in anti-de Sitter space can be in stable equilibrium even if the potential energy is unbounded from below, violating the weak energy condition. Hence there is no fundamental reason that black hole&#39;s horizons shou

Michael Mueger

We show that a large class of massive quantum field theories in 1+1 dimensions, characterized by Haag duality and the split property for wedges, does not admit locally generated superselection sectors in the sense of Doplicher, Haag and Roberts. Thereby the extension of DHR theory to 1+1 dimensions due to Fredenhagen, Rehren and Schroer is vacuous for such t

Michael Mueger

We consider the complete normal field net with compact symmetry group constructed by Doplicher and Roberts starting from a net of local observables in >=2+1 spacetime dimensions and its set of localized (DHR) representations. We prove that the field net does not possess nontrivial DHR sectors, provided the observables have only finitely many sectors. Whereas